The following figures are suggested when producing models for lava tube prospecting and use. By standardizing the figures used in models, this will ease the comparison of different models. This document is also a useful repository where people working in this field can find the required information quickly.
Some of the figures are estimates, and are marked as such. They should be treated with caution, and replaced with better figures as they become available.
Unless otherwise stated, all figures come from the Lunar Sourcebook and NASA's Handbook of Lunar Materials.
Individual lava flows are thin. They average of 60 feet (20m), some are less than 30 feet (10m) thick. Therefore, they cool quickly, but the viscosity of the melt is very low, so long flows can be found.
Sinuous rilles begin at craters (or crater-like landforms) and fade downslope in smooth mare surface. They occur mainly near basin margins.
Sizes: (from Lunar Orbiter photographs)
Terrestrial tubes form by the build-up of levees on either side of a lava channel. Levees eventually build up to form roofs.
On Earth, subsequent widening and deepening of the tubes is sometimes observed (due to the melting of the roofs and floor). On the moon, widths bridging more than 300 feet (100 meters) have been observed on Lunar Orbiter photographs.
Vp, Q, and regolith thicknesses come from the Active Seismic Experiments taken on the later Apollo Landers.
In sunlight, conductivity experiences approximately 10x106 times increase.
The above data comes from returned samples.
Estimates are based on typical data given in Dobrin M, Savit C, Introduction to Geophysical Prospecting (4th ed).
On Earth, conductivity surveys use AC to avoid electrolytic effects. As there's no water on the moon, these shouldn't exist, so DC and AC conductivities should be the same.
As no clear lava tubes have been found and measured, I propose the following dimensions for use as a standard model for the Artemis Project studies. These are based in part on observed dimensions of sinuous rilles.
Small Lava Tubes Large Lava Tubes Length undefined; very long undefined; very long Width 60 ft (20 m) 1000 ft (300 m) Height 45 ft (15 m) 300 ft (100 m) Depth 60 ft (20 m) 1500 ft (500 m)
Length could be several miles. The inifinite length assumption is of more use when creating synthetic responses to various geophysical techniques.
Depth is the distance from the surface of the moon to the ceiling of the lava tube. Of these, the depths are particularly rough and ready.
Additional References to Lava Tubes in the Artemis Data Book
How Lava Tubes Form
Section 8.4. Oregon Moonbase.
Uses for Lunar Lava Tubes